GREENVILLE, S.C. — Primary day at hand, fast-climbing Newt Gingrich told South Carolinians on Saturday that he was "the only practical conservative vote" able to stop front-runner Mitt Romney in the GOP presidential race. Romney acknowledged the first-in-the-South contest "could be real close" and prepared for an extended fight by agreeing to two more debates in Florida, next on the election calendar.

Former Pennsylvania Sen. Rick Santorum braced for a setback and looked ahead to the Jan. 31 contest after getting the most votes in Iowa and besting Gingrich in New Hampshire. Texas Rep. Ron Paul made plans to focus on states where his libertarian, Internet-driven message might find more of a reception with voters; his campaign said it had purchased a substantial ad buy in Nevada and Minnesota, which hold caucuses next month.

The first contest without Texas Gov. Rick Perry, who dropped out this past week and endorsed Gingrich, was seen as Romney's to lose just days ago. Instead, the gap closed quickly between the Massachusetts governor who portrays himself as the Republicans best positioned to defeat President Barack Obama and Gingrich, the confrontational former House speaker from Georgia.

Romney avoided a run-in with Gingrich at Tommy's Country Ham House, where both had scheduled campaign events for the same time. Romney stopped by the breakfast restaurant 45 minutes ahead of schedule. When Gingrich arrived, just minutes after Romney's bus left the parking lot, he said: "Where's Mitt?"

Earlier, Gingrich had a message for voters during a stop at The Grapevine restaurant in Boiling Springs not long after the polls opened: Come out and vote for me if you want to help deny Romney nomination.

He told diners who were enjoying plates of eggs and grits that he was the "the only practical conservative vote" to the rival he called a Massachusetts moderate. "Polls are good, votes are better," he said.

Romney's agreement to participates in Florida debates Monday in Tampa and Thursday in Jacksonville was seen as an acknowledgement of a prolonged battle with Gingrich.

"This could be real close," said Romney as he chatted on the phone with a voter Saturday morning and urged the man to go vote.

Before the ham house standoff that wasn't, Romney stood outside his Greenville headquarters and undertook a new attack on Gingrich. He called on Gingrich to further explain his contracts with Freddie Mac, the housing giant, and release any advice he had provided to the company. He has said the contracts earned two of his companies more than $1.6 million over eight years, but that he only pocketed about $35,000 a year himself.

'I'd like to see what he actually told Freddie Mac. Don't you think we ought to see it?" Romney said.

It was another response to pressure on Romney to release his tax returns before Republican voters finish choosing a nominee.

A day earlier, Romney had called on Gingrich to release information related to an ethics investigation of Gingrich in the 1990s. Gingrich argues that GOP voters need to know whether the wealthy former venture capital executive's records contain anything that could hurt the party's chances against Obama.

Romney has said he will release several years' worth of tax returns in April. Gingrich has called on him to release them much sooner. On Saturday, Romney refused to answer questions from reporters about the returns and whether his refusal to release them had hurt him with South Carolina voters.

Gingrich, buoyed by Perry's endorsement as he left the race Thursday, has called Romney's suggestion about releasing ethics investigation documents a "panic attack" brought on by sinking poll numbers.

The stakes were high for Saturday's vote. The primary winner has gone on to win the Republican nomination in every election since 1980.

It's very important, but it's not do or die," Paul told Fox News

Some of South Carolina's notorious 11th-hour devilry — fake reports in the form of emails targeting Gingrich and his ex-wife Marianne — emerged in a race known as much for its nastiness as for its late-game twists.

"Unfortunately, we are now living up to our reputation," said South Carolina GOP strategist Chip Felkel.

State Attorney Gen. Alan Wilson ordered a preliminary review of the phony messages to see if any laws had been broken.

Gingrich's ex-wife burst into the campaign this week when she alleged in an ABC News interview that her former husband had asked her for an "open marriage," a potentially damaging claim in a state where the Republican primary electorate includes a potent segment of Christian conservatives. The thrice-married Gingrich, who has admitted to marital infidelities, angrily denied her accusation.

Copyright 2012 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

Video: GOP primary stops in South Carolina

Closed captioning of: GOP primary stops in South Carolina

>>>now to politics in the southwest in the primary. the other two candidates say, hey, don't count them out yet. nbc's
peter alexander
is in columbia,
south carolina
, with the latest. good morning, peter.

>> reporter: good morning, amy. the polls are open in
south carolina
. really this is going down to the wire. after the wild week it's only fitting we're expecting another intense day of campaigning. the front-runner for much of this race,
mitt romney
is hoping to put the
republican primary
field to bed but his campaign has been trying to lower expectations in recent days. governor romney even telling nbc news late yesterday it's always been an uphill batter in the
state of south carolina
. meanwhile
newt gingrich
, a little closer to his home turf, remember he's from georgia, trying to get his first win for the primary season. the best metaphor is the fact that both romney and gingrich are expected to campaign in the same place at the same time today. you can call this the showdown at tommy's
country ham
house in greenville. the question, amy, is which candidate will blink first.

>>and, peter, obviously the latest poll shows gingrich could win tonight. what are the analysts saying?

>> reporter: it's a good question. it was only monday this week importantly before the last debate where we noticed the fact that
newt gingrich
was behind by about 15 percentage points. and then just in the last couple of days since the most recent debate where
newt gingrich
really went on the defensive, targeting the media where they said some reports were false about his ex-wife.